The source revealed Miley drinks and smokes weed before her performances because it enables her to be more creative. The singer has ditched her "party girl" image since reuniting with long-time beau Liam Hemsworth, but friends and family are worried the star is back-tracking.

"She just doesn't have a stop button, which in her case, can be dangerous," the source continued.

For more on Miley Cyrus, pick up the latest issue of In Touch, on newsstands now!